Is Younger Age a Risk Factor for Failure Following Aseptic Revision Total Knee Arthroplasty?

Revision total knee arthroplasties (rTKAs) are being performed more frequently in the United States in younger patients. Few large studies have evaluated the effect of age following rTKA. The study sought to evaluate the effect of age on rTKA outcomes.

The American Joint Replacement Registry was used to identify aseptic rTKAs in younger (18 to 64 years, n = 32,631) and older (> 65 years, n = 43,992) patients from January 2012 to September 2020, allowing for a minimum 2-year follow-up. The mean age was 56 years in the younger cohort and 73 years in the older cohort. The mean follow-up was 5.4 years. Sex and body mass index were similar between groups. Kaplan-Meier survivorship analysis was performed with rerevision as the primary endpoint. Secondarily, multivariate analyses were performed to adjust for demographics and comorbidities.

The proportion with rerevision was higher in the younger cohort compared to the older (8.1 versus 5.4%, P < 0.001). The 10-year survivorship free of all-cause rerevision was 90.2% (95% confidence interval [CI]: 89.7 to 90.7) in the younger cohort versus 93.7% (95% CI: 93.4 to 94.1) in the older cohort (P < 0.0001). Younger age was significantly associated with a higher adjusted hazard ratio (HR) for all-cause rerevision (HR: 1.4, 95% CI: 1.3 to 1.6), as were men (HR: 1.4, 95% CI: 1.2 to 1.5) and initial revision for instability (HR: 1.3, 95% CI: 1.1 to 1.5). In a subgroup analysis of patients aged < 65 years, a 5-year decrease in age was associated with a 10.0% increase in risk of rerevision. Indications for rerevisions differed among the younger and older cohorts (P < 0.01): infection (30.2 versus 34.9%), aseptic loosening (19.0 versus 15.8%), and instability (12.2 versus 12.7%).

Younger age, men, and initial revision performed for instability were associated with significantly increased risk for all-cause rerevision following aseptic rTKA. Notably, age may have a continuous effect on rerevision rates, as each 5-year decrease in age was associated with a 10% increase in risk of rerevision. Future research may further elucidate these increased risks in this younger patient population.